Alterations in thymic and bone marrow lymphocyte subpopulations in GnRH agonist treated prepubertal female mice

Role of gender in multiple sclerosis: clinical effects and potential molecular mechanisms

Multiple sclerosis (MS) is more prevalent in females than males, and this female predominance is increasing as time goes by. Additionally, gender appears to play critical roles in development, progression and treatment of MS, and is therefore an aspect that should always be considered in the design and interpretation of research and clinical trials for MS. In this review, factors that could potentially explain the gender-biased observations in MS are discussed. These include sex-specific differences between the male and female immune systems and nervous systems, genetic and epigenetic or environmental-related effects, the effects of gonadal hormones, and materno-fetal interactions.

Gonadotropin-releasing hormone agonist administration affects the thymopoiesis in adult female rats independently on gonadal hormone production

PROBLEM

In addition to having an indirect effect on the T-cell development by controlling the production of ovarian steroids, an accumulating body of evidence suggest that GnRH analogue (GnRH-A) administration may exert a thymopoietic regulatory effect that is not mediated by ovarian hormones.

METHOD OF STUDY

In non-ovariectomized (non-OVX) and OVX adult female AO rats treated s.c. with GnRH-A or saline (controls), over 14 days, were estimated the thymic cellularity and thymocyte expression of CD4/CD8/TCRalphabeta by stereological analysis and three-color flow cytometry, respectively.

RESULTS

GnRH-A in both groups of rats diminished the thymic cellularity. In non-OVX rats GnRH-A increased the relative numbers of immature cells (CD4-8-TCRalphabeta(-), CD4-8-TCRalphabeta(low) and CD4+8-TCRalphabeta(low)), and reduced those of positively selected CD4+8+TCRalphabeta(high) and mature (CD4-8+TCRalphabeta(high), CD4(+8)-TCRalphabeta(high)) cells, suggesting decelerated expression of TCRalphabeta followed by less efficient positive selection and further maturation of the selected cells. Differently, in OVX rats GnRH-A decreased the percentage of immature (CD4-8-TCRalphabeta(-), CD4+8+ TCRalphabeta(-)) cells and increased those of all TCRalphabeta(high) subsets, suggesting an increased rate of early thymocyte differentiation, more efficient positive selection and further maturation of the selected cells.

CONCLUSIONS

The effect of GnRH-A administration is affected by the presence of ovarian steroids.

Effect of gonadotropin-releasing hormone agonists on monocyte chemotactic protein-1 production and macrophage infiltration in leiomyomatous uterus

OBJECTIVE

The level of monocyte chemotactic protein-1 (MCP-1), a potent chemoattractant for monocytes, is fivefold higher in myometrium than in leiomyoma. We have previously shown that myometrium from women using GnRH agonists (GnRH-a) express the highest levels of MCP-1, which has antiproliferative effects on leiomyoma cells. We hypothesized that MCP-1 may have a direct paracrine effect in leiomyomatous uterus rather than acting by way of chemoattraction of macrophages.

DESIGN

Cross-sectional study.

SETTING

University medical center.

PATIENT(S)

Women with leiomyoma (n = 32).

INTERVENTION(S)

Immunohistochemical analysis performed in the myometrium and leiomyoma of women receiving (n = 11) and not receiving (n = 21) GnRH-a treatment.

MAIN OUTCOME MEASURE(S)

The MCP-1 levels and macrophage counts determined by immunohistochemistry in the myometrium and leiomyoma of women receiving GnRH-a were compared to the levels and counts in women not receiving GnRH-a.

RESULT(S)

Samples from all 11 patients using GnRH-a revealed strong MCP-1 staining, whereas staining was only weakly present in 11 and absent in 10 samples from patients not receiving GnRH-a, revealing a significant difference in MCP-1 expression between GnRH-a users versus nonusers (P=.006). The number of tissue macrophages between GnRH-a users and nonusers was not significantly different.

CONCLUSION(S)

We found that there is an increase in the MCP-1 protein expression in the myometrium of women receiving GnRH-a treatment. On the other hand, we have not observed a difference in the macrophage count and distribution with GnRH-a treatment, suggesting a potentially direct antiproliferative role for MCP-1 rather than acting by means of chemoattraction of macrophages.

Effect of neonatal treatment with a gonadotropin releasing hormone antagonist on developmental changes in circulating lymphocyte subsets: a longitudinal study in male rhesus monkeys

We have examined changes in circulating lymphocyte subsets from the neonatal period until adulthood (4 months until 5.5 years of age) in male rhesus monkeys, and the impact of neonatal treatment with a GnRH antagonist (Ant) or Ant and androgen (Ant/And) on these parameters. Absolute numbers of lymphocytes, B cells, total T lymphocytes, and CD4+ T cells decreased, neutrophils increased, and CD8+ T cells did not change with age. WBC counts increased between 4 mo and 2 years of age and then fell to neonatal levels over the next two years. The decline of CD4 + T cells in association with stable CD8+ T cell levels resulted in an age-related decrease in the CD4+/CD8+ T cell ratio. At 4 months of age, WBC's, lymphocytes, total T cells, CD8+ T cells and B cells were lower in Ant- and Ant/And-treated animals compared to controls. With the exception of WBC counts, these values had normalized by 2 years of age. Reduced WBC levels in treated animals persisted through adulthood. CD4+ T cell levels tended to be lower in Ant-treated and higher in Ant/And-treated animals than in controls at 4 months of age. CD4+ T cells remained lower in Ant- than in Ant/And-treated animals at most ages. The higher CD4 + T cell counts in Ant/And-treated animals resulted in an elevated CD4 + /CD8 + T cell ratio that persisted until the onset of year 5. During years 5 and 6, seasonal fluctuations in WBC's and neutrophils were observed with counts being higher in the breeding (fall) than in the nonbreeding (summer) season. The data document that developmental changes in circulating immune cells in the rhesus monkey are qualitatively similar to those reported in humans, and provide further evidence that neonatal treatment of male rhesus monkeys with Ant or Ant/And may alter early programming of the immune system.

Changes in lymphoid tissue after treatment with a gonadotropin releasing hormone antagonist in the neonatal marmoset (Callithrix jacchus)

PROBLEM

The effect of neonatal treatment with a gonadotropin releasing hormone (GnRH) antagonist on the morphology and distribution of lymphocytes in lymphoid tissue of the infant marmoset was examined.

METHOD OF STUDY

From a screened panel of antihuman antibodies for specific immune cells, antibodies for the CD20 and CD3 antigens showed excellent reactivity with marmoset tissue. Five sets of marmoset twins were treated with either the GnRH antagonist or a vehicle from birth, and were euthanized at 7 to 9 (3 sets) or 16 to 20 weeks (2 sets) of age. The spleen, thymus, and inguinal lymph nodes from each animal were processed for immunocytochemistry, and the number of cells expressing the CD20 and CD3 antigens were quantified.

RESULTS

Control twins exhibited high plasma levels of testosterone, characteristic of the neonatal period, whereas testosterone concentrations were reduced (P = 0.001) to detection limits in the GnRH antagonist-treated twins. Microscopic evaluation suggested that treatment reduced the volume and cellularity of the thymic cortex, resulting in a decrease in the cortical-to-medullary ratio. Treatment reduced (P = 0.046) the number of thymocytes expressing the B-cell antigen (CD20) and marginally lowered (P = 0.067) the number expressing the T-cell antigen (CD3) in the thymic medulla. In the spleens of treated animals, periarterial lymphatic sheaths were less prominent on microscopic examination, and there were marginally fewer (P = 0.064) CD3+ cells. Numbers of CD20+ lymphocytes in the peripheral white pulp of the spleen and in the germinal centers of the lymph nodes, or CD3+ cells in the paracortex and germinal centers of the lymph nodes, were not altered by treatment.

CONCLUSION

Neonatal treatment with a GnRH antagonist may alter maturational processes for B and T cells in the thymus and spleen of the marmoset and may deprive the immune system of its normal sensitivity to GnRH at a potentially critical time in development.

Gonadotropin-releasing hormone agonist influences absolute levels of lymphocyte subsets in vivo in male mice

Our earlier studies have demonstrated that gonadotropin-releasing hormone (GnRH) agonists suppress immune system function in female mice. No systematic studies regarding the effect of gender on immune system function following GnRH agonist treatment, however, have been reported. This study, therefore, investigated sequential changes in lymphocyte subsets in 3- and 10-week-old male mice following agonist or placebo administration. Changes in immunophenotypic expression of lymphocytes from thymus, bone marrow, spleen, and blood were analysed at periodic intervals. Upon agonist administration, plasma testosterone levels were significantly increased in pre-pubertal mice, but were significantly decreased in post-pubertal males. Absolute thymic weights, thymocytes and T subsets were significantly increased from the third week regardless of gonadal status. Blood lymphocyte subsets showed a decreasing trend after agonist administration in pre-pubertal males, whereas no differences were observed in post-pubertal males. No significant differences were observed in spleen cells after agonist administration. These studies, together with earlier observations in female mice indicate that GnRH agonist effects on the immune system, are independent of steroid hormone levels. In contrast to suppressive effects in females, GnRH agonist induce no change or ultimately enhanced lymphocyte counts in males, indicating differential effects on the immune system between males and females. This may have important implications for the treatment of various diseases.

Hematopoietic stem cell antigen-1 (Sca-1) expression in different lymphoid tissues of female mice treated with GnRH agonist

PROBLEM

Our earlier studies have demonstrated a general suppression of leukocyte maturation upon GnRH agonist treatment in mice and suggested a potential effect at an early stem cell stage of leukocyte development.

METHOD

Three-week old Balb/c and C57BL/6 female mice received 50 micrograms injections of Lupron depot or placebo. Sequential changes in Sca-1+ cells in the bone marrow, thymus, blood and spleen were studied by flow cytometry.

RESULTS

In bone marrow, the absolute numbers of Sca-1+ cells were significantly decreased at 2 weeks in C57BL/6 mice whereas a decreasing trend was noted in Balb/c mice following agonist administration. Concomitantly, thymocytes expressing Sca-1+ cells were significantly increased at 2 weeks in C57BL/6 mice, but were significantly decreased in Balb/c mice. Significant decreases in Sca-1+ cells were also observed in spleen and blood in Balb/c mice whereas no significant differences were observed in C57BL/6 mice.

CONCLUSIONS

These data suggest GnRH agonists affect hematopoietic stem cell development in mice. The effects observed vary with different genetic backgrounds. In Balb/c mice these effects are more pronounced, and appear to result in the inhibition of stem cell maturation. In contrast, GnRH agonist enhances stem cell maturation in C57BL/6 mice.

In vivo CD3+CD25+ lymphocyte subpopulation is down-regulated without increased serum-soluble interleukin-2 receptor (sIL-2R) by gonadotropin releasing hormone agonist (GnRH-a)

PROBLEM

To test further whether the suppression of the CD3+CD25+ lymphocyte subpopulation by gonadotropin-releasing hormone agonist (GnRH-a) is related to the change in levels of cytokines and soluble interleukin-2 receptor (sIL-2R).

METHOD

Twenty-seven infertile patients were enrolled under the long protocol of GnRH-a agonist (buserelin acetate) and superovulation with gonadotropin from our IVF-ET program. Peripheral B cells, NK cells, CD4+ and CD8+ T cells and the expression of CD69, CD25, HLA-DR, and CD71 antigens on the T cells were serially examined by dual-color flow cytometry. Serum levels of cytokines and sIL-2R were measured.

RESULTS

The B cells, NK cells, T cells, CD4+, CD8+ T cells, CD3+DR+, and CD3+CD71+ lymphocyte subpopulations were not changed after the use of GnRH-a. The CD25+ T cell subpopulation was significantly down-regulated, but the CD69+ T cell subpopulation was increased when the GnRH-a was used for approximately 2 wk. The serum levels of interleukin-1 beta (IL-1 beta), interleukin-2 (IL-2), interleukin-4 (IL-4), interferon-gamma (IFN-gamma), and sIL-2R were not changed.

CONCLUSION

The GnRH-a had a transiently suppressive effect on CD25+ T cells, but a stimulatory effect on CD69+ T cells. However, the serum level of cytokines or sIL-2R did not change. These immunological modulations seems to be the result of interaction between GnRH-a and estrogen.

Effects of GnRH antagonist on lymphocyte subpopulations in primary and secondary lymphoid tissues of female mice

PROBLEM

GnRH analogs are playing an increasing role in the treatment of many clinical disorders. Recent studies have indicated that GnRH agonists suppress immune function in mice in vivo. The present study investigated the effects of GnRH antagonist of functional lymphocyte subsets of mice in vivo.

METHOD

Three- and 10-wk old female mice received 10 micrograms of Nal-Glu daily for 15 and 30 days; changes in the immunophenotypic expression of lymphocytes from thymus, bone marrow, spleen and blood were analyzed by flow cytometry.

RESULTS

The administration of GnRH antagonist to pre- and postpubertal female mice induced slight increases in lymphocyte subpopulations in primary and secondary lymphoid tissues. These effects are opposite those obtained with GnRH agonist in our earlier studies in mice.

CONCLUSIONS

Assuming similar effects in humans and rodents, the gonadal steroid suppression achieved by GnRH antagonist treatment has no apparent suppressive effects on the immune system.